Use the -q flag when calling port

The -q flag suppresses any output other than port names, eliminating the need to
further modify output.

src/_port

@@ -135,8 +135,14 @@ _port() {
     '-y[Perform a dry run.]' \
     '-t[Enable trace mode debug facilities on platforms that support it (Mac OS X).]' \
     "1:Port actions:(($actions))" \
-    '*:extra:_port_dispatch' \
+    '*:extra:->extra' \
     && return 0
+
+  case "$state" in
+    extra)
+      _port_dispatch
+      ;;
+  esac
 }
 
 _port_dispatch() {
@@ -219,16 +225,8 @@ _port_select() {
 }
 
 _port_caching_policy() {
-  local reg_time comp_time check_file
-  case "${1##*/}" in
-    PORT_INSTALLED_PACKAGES)
-      check_file=$port_prefix/var/macports/registry/registry.db
-      ;;
-    PORT_AVAILABLE_PACKAGES)
-      check_file=${$(port dir MacPorts)%/*/*}/PortIndex
-      ;;
-  esac
-  reg_time=$(stat -c '%Z' $check_file)
+  local reg_time comp_time
+  reg_time=$(stat -c '%Z' $port_prefix/var/macports/registry/registry.db)
   comp_time=$(stat -c '%Z' $1)
   return $(( reg_time < comp_time ))
 }